content: /* Copyright (C) 2016-2018 Alibaba Group Holding Limited
  
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at
  
      http://www.apache.org/licenses/LICENSE-2.0
  
  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  ==============================================================================*/
  
  // Protocol Buffers - Google's data interchange format
  // Copyright 2013 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package com.google.protobuf.nano;
  
  import java.io.IOException;
  
  /**
   * Base class of those Protocol Buffer messages that need to store unknown fields,
   * such as extensions.
   */
  public abstract class ExtendableMessageNano<M extends ExtendableMessageNano<M>>
          extends MessageNano {
      /**
       * A container for fields unknown to the message, including extensions. Extension fields can
       * can be accessed through the {@link #getExtension} and {@link #setExtension} methods.
       */
      protected FieldArray unknownFieldData;
  
      @Override
      protected int computeSerializedSize() {
          int size = 0;
          if (unknownFieldData != null) {
              for (int i = 0; i < unknownFieldData.size(); i++) {
                  FieldData field = unknownFieldData.dataAt(i);
                  size += field.computeSerializedSize();
              }
          }
          return size;
      }
  
      @Override
      public void writeTo(CodedOutputByteBufferNano output) throws IOException {
          if (unknownFieldData == null) {
              return;
          }
          for (int i = 0; i < unknownFieldData.size(); i++) {
              FieldData field = unknownFieldData.dataAt(i);
              field.writeTo(output);
          }
      }
  
      /**
       * Checks if there is a value stored for the specified extension in this
       * message.
       */
      public final boolean hasExtension(Extension<M, ?> extension) {
          if (unknownFieldData == null) {
              return false;
          }
          FieldData field = unknownFieldData.get(WireFormatNano.getTagFieldNumber(extension.tag));
          return field != null;
      }
  
      /**
       * Gets the value stored in the specified extension of this message.
       */
      public final <T> T getExtension(Extension<M, T> extension) {
          if (unknownFieldData == null) {
              return null;
          }
          FieldData field = unknownFieldData.get(WireFormatNano.getTagFieldNumber(extension.tag));
          return field == null ? null : field.getValue(extension);
      }
  
      /**
       * Sets the value of the specified extension of this message.
       */
      public final <T> M setExtension(Extension<M, T> extension, T value) {
          int fieldNumber = WireFormatNano.getTagFieldNumber(extension.tag);
          if (value == null) {
              if (unknownFieldData != null) {
                  unknownFieldData.remove(fieldNumber);
                  if (unknownFieldData.isEmpty()) {
                      unknownFieldData = null;
                  }
              }
          } else {
              FieldData field = null;
              if (unknownFieldData == null) {
                  unknownFieldData = new FieldArray();
              } else {
                  field = unknownFieldData.get(fieldNumber);
              }
              if (field == null) {
                  unknownFieldData.put(fieldNumber, new FieldData(extension, value));
              } else {
                  field.setValue(extension, value);
              }
          }
  
          @SuppressWarnings("unchecked") // Generated code should guarantee type safety
          M typedThis = (M) this;
          return typedThis;
      }
  
      /**
       * Stores the binary data of an unknown field.
       *
       * <p>Generated messages will call this for unknown fields if the store_unknown_fields
       * option is on.
       *
       * <p>Note that the tag might be a end-group tag (rather than the start of an unknown field) in
       * which case we do not want to add an unknown field entry.
       *
       * @param input the input buffer.
       * @param tag the tag of the field.
  
       * @return {@literal true} unless the tag is an end-group tag.
       */
      protected final boolean storeUnknownField(CodedInputByteBufferNano input, int tag)
              throws IOException {
          int startPos = input.getPosition();
          if (!input.skipField(tag)) {
              return false;  // This wasn't an unknown field, it's an end-group tag.
          }
          int fieldNumber = WireFormatNano.getTagFieldNumber(tag);
          int endPos = input.getPosition();
          byte[] bytes = input.getData(startPos, endPos - startPos);
          UnknownFieldData unknownField = new UnknownFieldData(tag, bytes);
  
          FieldData field = null;
          if (unknownFieldData == null) {
              unknownFieldData = new FieldArray();
          } else {
              field = unknownFieldData.get(fieldNumber);
          }
          if (field == null) {
              field = new FieldData();
              unknownFieldData.put(fieldNumber, field);
          }
          field.addUnknownField(unknownField);
          return true;
      }
  
      @Override
      public M clone() throws CloneNotSupportedException {
          M cloned = (M) super.clone();
          InternalNano.cloneUnknownFieldData(this, cloned);
          return cloned;
      }
  }
  